The present invention relates to the use of porous calcium carbonate, especially porous coral skeleton, as a support material for in vitro cultivation of eukaryotic or prokaryotic cells.
It is known that most eukaryotic cells can be cultivated in vitro only on a solid support. Such cultivation is generally carried out in containers or flasks in which cell multiplication stops when a monocellular layer completely covers the portion of the wall in contact with the liquid nutrient medium.
Such cultivation methods have the drawback of necessitating the handling of a large number of containers.
Moreover, eukaryotic cells do not grow on some materials, and it is not possible to predict whether a given material will be suited to the in vitro cultivation of these cells.
There is, at the present time, a considerable need for in vitro cultivation of eukaryotic cells in various fields.
For example, the in vitro cultivation of plant cells is capable of enabling natural substances to be produced and isolated without experiencing the limitations and hazards of cultivation on open ground.
Plant cells are markedly more sensitive than bacteria to the shearing effects caused by the systems usually employed in fermenters. It is hence advantageous to cultivate these cells on a solid support. Under the action of hormones, the concentration of which is defined in each case, any fragment of a plant may be cultivated in the isolated state and under sterile conditions. Undifferentiated cells (calluses) are capable of synthesizing metabolites which are normally to be found only in certain specific organs of the plant.
At the present time, medicinal active principles are the foremost substances produced, as well as various essential oils, flavorings, colorings and pesticides whose molecular complexity makes chemical synthesis too difficult and/or too expensive.
As applications of plant cell cultures, there may be mentioned:
production of anthraquinones by GALLIUM APARINE; PA1 production of an anticancer drug, tripdiolide, by TRYTERIZHIUM WILFORDII; PA1 production of an antispasmodic (atropine) by ATROPE BELLADONA; PA1 production of alkaloids by PAPAVER SOMNIFERUM.
Furthermore, plant cells maintained in vitro often have strong capacities for bioconversion. For example, a salicylic acid derivative possesses faster analgesic activity than that of aspirin, as well as better gastric tolerability.
Similarly, it is desirable to be able to cultivate many animal cells in vitro, for example for medical purposes. Bone marrow cells which are precursors of the cells of the immune system are known to be very difficult to cultivate in vitro, although such cultivation is of great value in the field of allografts or autografts.
The value of a good cell multiplication in vitro extends to cells modified by genetic recombination. Up to now, such cells can, in practice, be cultivated only if they are immortalized by hybridization with cancer cells or by transformation using a virus.
Another value of the cultivation of cells in vitro would be, in a patient suffering from an existing or foreseeable loss of bone substance, the withdrawal of bone cells from this patient, the cultivation of these cells in vitro on a suitable support, and subsequently the introduction of said support comprising the cells thus cultivated in order to make good the loss of substance. It is known, in effect, that coral can constitute a biodegradable bone prosthesis, the reoccupation of which by bone as degradation takes place will be promoted by cultivated cells reintroduced in this way.
It is also advantageous to improve the methods of cultivation of cell lines such as CHO and VERO lines, or hybridomas, for the purpose of production of proteins, vaccines, hormones, antibodies, and the like.
The same applies to the cultivation of insect cells for the purpose of production of recombinant proteins or of viruses (for example baculoviruses).
Another field of interest is the cultivation of filamentous fungi, in particular ascomycetes, especially yeasts (for example Aspergillus, Penicillium, and the like). There may be mentioned, more especially, the cultivation of A. FLAVIUS for the production of aflatoxins or the cultivation of A. NIGER for the production of various organic acids.